There are a lot of them about nowadays. Zombies, I mean. In the world of adult books there's been all that fuss about Pride and Prejudice and Zombies by the American author Seth Grahame-Smith (with more than a little help from Jane Austen, of course). Not very long ago, the Big Brother house was overrun with zombies in Channel 4's Dead Set – written by this paper's very own Charlie Brooker. And, before either of these, there was the cult British film Shaun of the Dead.

The enemy in Charlie Higson's new series of children's books, beginning with The Enemy, aren't zombies in the truest sense. They aren't dead. But, that minor detail aside, they exhibit many traditional zombie characteristics: they look as though they're falling to bits, are shabbily dressed, not too bright, amble about in disorganised groups, are genuinely frightening, and they eat children. You see, in Higson's post-apocalyptic London, it's the adults who have been affected by some dreadful something, and the children – who are unaffected – are their prey.

The children of London have split into groups. We first learn of the Waitrose and the Morrisons, named – you guessed it – after the supermarkets they use as fortresses against the grown-ups. What's not clear is how or if the general terminology for the zombie-like adults spread. Rather than being men or women, they're described as mothers and fathers, as living in nests, and being infestations.

The problem with the zombie genre much of the time is the "so what?" factor. Shaun of the Dead, for example, was a British let's-go-down-the-pub antidote to Night of the Living Dead, but I was still left feeling "and . . . ?" Dead Set was a great idea, but might have been all the better for staying just that.

Where Higson has been clever is in never losing sight of the fact that – however fast-paced or exciting or gory or inventive or just plain gross he's being – it's ultimately the characters that matter. The more we get to know the protagonists (and their numbers vary as key characters are killed), the more believable they become and the more we care about them.

Things really begin to change for the Waitrose crew when they team up with Morrisons and journey across London to Buckingham Palace, where, they are told, there is a large, self-sufficient, safe community of children. Getting there is the real challenge, with not just the marauding gangs of mothers and fathers to evade, but also the feral animals escaped, long ago, from London Zoo.

In a society where children are demonised daily by sections of the media, it's good to have an adventure in which the tables are clearly turned. Having said that, The Enemy is largely written from the perspective that, before the pandemic, adults were loving and "safe". One can't help but wonder about those child readers who lose themselves in a book to try to escape the very real adult terrors of their own.

Interestingly, Higson leaves us to ponder who the real enemy in The Enemy might be. Just as in life, having a common enemy doesn't mean that there is harmony in the ranks. These are children of varying ages having to go through the usual growing pains in very unusual circumstances. We are left with the possibility that, even in a post-apocalyptic world, humans – whether boys or girls – are their own worst enemies.